The present invention refers to the reducers for combustible gases or l.p.g. used for feeding internal combustion engines and housed in bottles. These combustible gases are employed for feeding internal combustion engines for motor transport or for stationary equipment.
Since the pressure of the gas housed in the bottle decreases progressively with its consumption from a value of several hundreds of bars to zero, the uncontrolled forces to which the lever in the pressure regulator is subjected vary from some hundreds of Newtons (or N. x m.) to zero. In the first case, the uncontrolled forces are equal to the forces which the lever receives from the controlling diaphragm of the flow rate and the outlet pressure of the gas; in the second case they are zero. The precise degree of adjustment is negatively affected to a marked degree by the progressively decreasing variation of these forces.
As a result of the lack of precise adjustment and particularly when the pressure of the gaseous fuel is high, irregularities occur in the idling speed of the motor, consumption is higher than usual, and there is an uncontrollable emission of pollutants.
The irregularities in the slow running of the engine, the increased consumption and emission of polluting gases are aggravated by the differences in the amount of heat, which in standard water heat exchangers installed in the traditional pressure reducers is transmitted to the outflowing fuel emitted in a gaseous state by the reducer.
U.S. Pat. No. 1,450,236 refers to a pressure reducer according to the preamble of independent claim 1 herein; in a supporting body of said reducer a chamber is housed, the chamber presents an entrance and an outlet which are respectively connected with a source of a compressed fluid and a device of use.
A compensating mechanism is capable of cancelling the momentum which results from the action of the gas pressure on a manoeuvring device which is controlled by a main diaphragm of the reducer.
The manoeuvring device comprises a two-arm lever which pivots on a pivot fulcrum under the action both of a plunger, which acts the first arm and a spring which urges the second arm of the lever. In addition the lever is mechanically connected with the main diaphragm.
EP-A-0 182 952 discloses an electrically heated reducer for compressed gas or l.p.g. having electrical resistors connected with the feeding system of the engine placed in contact with the walls of the reducer body.
Said resistors are housed in a notch of an inner wall of the reducer and maintained adherent to the lower surface of said wall by means of springs placed between the upper surface of resistors and the lower surface of a metal plate fixed to the upper surface of said wall.
The purpose of this invention is to obviate these disadvantages.
The invention, as claimed, solves the problem by creating a pressure reduction unit which is self-compensating and electrically heated for compressed gases or l.p.g., by means of which the resulting thrust or the consequent momentum arising from the thrusts on the regulation lever, due to the pressure of the fuel contained in the bottle, are reduced to zero whatever the pressure, and the fuel which is emitted in a gaseous state from the reducer is heated to the same amount of heat per unit of mass of fuel supplied in every thermic state of the engine.
The advantages of the present invention lie in the possibility of controlling the pressure and maintaining constant the temperature of the fuel which is fed by the pressure reducer for every value of the pressure of the fuel contained in the bottle. This is achieved by means of the diaphragm and of the specially placed electrical resistors in the regulator. In this way, the regular idling speed of the engine, a measured consumption of fuel and a limited and controlled emission of pollutants may be obtained.